all the key does is take preload off the front. Softens it up, weight of the vehicle brings the truck lower. What that will also do is make it more likly you will hit a dip, pot hole, etc, where normally the stiffer spring rate would have supported the truck and it would be fine… you will bottom out alot easier.
Same as torsion bar lift “kits”… it spins it up stiffer to put more preload on the suspenion. the weight on the front end didnt change so it lifts it up. This makes it ride like a brick becasue the suspension doenst compress as it should over bumps. it also stresses the bar and makes it more likly that it could crack.
Spindle up front. it will drop it 2 inches, and NOT effect spring rate… ie it will ride the same as it does now.